Question

define alpha and beta . Derive the relation between them.​

Answer 1

Answer:

α and β are two important parameters in the transistor which define the current gains in the transistor.

α=

I

E

I

C

β=

I

B

I

C

Since I

C

>I

B

; β is very large and its value lies between 15 and 50.

Since I

C

<I

e

; so α<1;

Its value lies between 0.95 and 0.99.

Relation between α and β:

I

E

=I

B

+I

C

Divide by I

C

,

I

C

I

E

=

I

C

I

B

+1

I

E

I

C

=α,

I

B

I

C

=β

So,

α

1

=

β

1

+1 or β=

1−α

α

β=100

100=

1−α

α

α=

101

100

Also, β=

I

B

I

C

=100

⇒I

C

=I

B

×100=50×10

−6

×100

=5×10

−3

=5mA

⇒I

E

=5×10

−3

+0.05×10

−3

=5.05×10

−3

Ampere or, 5.05 mA.